(1) Field of the Invention
The invention is concerned with a solenoid actuator for use with electromagnetic valves.
(2) Description of the Prior Art
Magnetic frames which have hitherto been employed in general solenoid actuators for use with electromagnetic valves are structured, for instance, as a so-called cover type having a cover placed over the top of coil and a flux plate fitted therebelow, and a so-called frame type having a pair of frames abutted against the sides of coil so as to form a magnetic frame. It has, however, been recognized experimentally that good results are obtainable for the structure of such magnetic frames where they have neither gaps nor acute corners across the magnetic circuit. Thus, the cover type structure is defective in being liable to form gaps in the juncture between the cover and the flux plate due to errors resulting in the fabrication thereof or deformations caused by external forces upon mounting the coil, and leading to large magnetic resistance by the gaps. The frame type structure also has the drawbacks of requiring complicated fabrication and being high in cost.